Host Dan Zehner meets up with geotechnical engineer Brady Cox, professor of engineering at Utah State University and co-PI at the NHERI @ University of Texas mobile shaker facility. Cox introduces the UTexas mobile shakers, huge vehicles that simulate a range of ground motions for studying earthquakes. There’s “T-Rex,” perhaps the world’s only shaker capable of generating large dynamic forces in any of three directions — vertical, horizontal in-line, and horizontal cross-line. And the custom-built “Liquidator,” weighing in at 70,000 pounds, which shakes vertically at very low frequencies; its longer waves help researchers look deeper into the ground.
Cox describes how engineers deploy the NHERI mobile shaker fleet around the world to study ground-based infrastructure like levees, soils that are prone to liquefaction, and civil structures like bridges.
Natural hazards engineers at the University of Texas are using fiber optic cable for subsurface and structural sensing. It’s called distributed acoustic sensing, or DAS, and it is much more efficient than traditional geophones or accelerometers. By sending laser light pulses through fiber optic cables — which are ultra-sensitive to light deflections — researchers can measure ground disturbances for up to 30 meters.
NHERI at UTexas website: https://utexas.designsafe-ci.org/
Short video shows how a shaker truck is used to characterize soil: https://www.youtube.com/watch?v=5cGbMggwxog
More about Brady Cox’s research: https://engineering.usu.edu/cee/people/faculty/cox-brady
Subsurface geotechnical imaging, as with levees:
https://www.youtube.com/watch?v=IS-qn06pVOw&list=PL2GxvrdFrBlma1A6IMfMasP-RP8ku5s2N&index=1
Testing for liquefiable soils:
https://www.youtube.com/watch?v=5cGbMggwxog&list=PL2GxvrdFrBlma1A6IMfMasP-RP8ku5s2N&index=2
Structural health monitoring:
https://www.youtube.com/watch?v=HRX-WMumpDQ&list=PL2GxvrdFrBlma1A6IMfMasP-RP8ku5s2N&index=3
NHERI at UTexas recently presented a workshop on DAS technology, including a live demonstration of a levee in Blackhawk, Louisiana. View the workshop recordings here.
Interested in using NHERI Mobile Shakers in your work, or want to learn more? Contact us!
